Method and apparatus for testing for color vision loss

ABSTRACT

A method and apparatus for administering eye tests to identify cone sensitivity loss associated with hereditary and acquired color vision loss which may be used for early detection, progress, treatment, and monitoring of eye conditions, traumatic brain injury, optic neuritis, systemic and neurological diseases including Glaucoma, Retinopathy, Age-Related Macular Degeneration, Multiple Sclerosis, Alzheimer&#39;s Disease, and Parkinson&#39;s Disease and retinal toxicity. Particularly, the method and apparatus disclosed uses a Cone Contrast Test (CCT) to test individuals for hereditary or acquired color vision loss associated with (a) early signs of potential disease/damage/toxicity in an effort to (i) provide opportunity for treatment, and (ii) prevent permanent eye damage, and (b) monitor progress and treatment of such disease/damage/toxicity. The system comprises a computer system including an input device and a display device, and the accuracy and repeatability of the testing is provided by repeated calibration using a colormeter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent is a Continuation of patent application Ser. No. 13/887,272,filed May 3, 2013 and claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application No. 61/642,378, filed May 3, 2012 andU.S. Provisional Patent Application No. 61/642,292, filed May 3, 2012which applications are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made in the performance of a Cooperative Research andDevelopment Agreement with the Department of the Air Force. TheGovernment of the United States has certain rights to use the invention.

REFERENCE TO COMPUTER PROGRAM LISTING APPENDIX

The present application includes the following computer program listingappendix. The computer program listing appendix is expresslyincorporated herein by reference in its entirety. The appendix containsan ASCII text file of the computer program as follows:

AdminWindow.txt 15.6 KB Created 5/3/2013 AdminWindow-2.txt 8.93 KBCreated 5/3/2013 app.txt .5 KB Created 5/3/2013 appmanifest.txt 2.44 KBCreated 5/3/2013 Browser.txt 2.63 KB Created 5/3/2013 Browser-2.txt 2.79KB Created 5/3/2013 FileIO.txt 1.29 KB Created 5/3/2013 HtmlReport.txt108 KB Created 5/3/2013 IniBS.txt 1.62 KB Created 5/3/2013LogInWindow.txt 2.78 KB Created 5/3/2013 LogInWindow-2.txt 3.38 KBCreated 5/3/2013 MainWindow.txt 70.7 KB Created 5/3/2013MainWindow-2.txt 26.9 KB Created 5/3/2013 mod1.txt 294 KB Created5/3/2013 mod3.txt 175 KB Created 5/3/2013 mod4.txt 67.5 KB Created5/3/2013 PatientsWindow.txt 13.0 KB Created 5/3/2013 colortest.txt 38.5KB Created 5/3/2013 form1.txt 24.4 KB Created 5/3/2013

FIELD OF THE INVENTION

The present method and apparatus relate to eye tests for hereditary andacquired color vision loss and may be used for the early detection,progress, treatment and monitoring of eye conditions, optic neuritis,traumatic brain injury, systemic and neurological diseases includingGlaucoma, Retinopathy, Age-Related Macular Degeneration, MultipleSclerosis, potentially Alzheimer's Disease and Parkinson's Disease, aswell as Retinal Toxicity due to high-risk medications. Particularly, thesystems and methods disclosed herein use a Cone Contrast Test (CCT) toidentify hereditary color deficiency and acquired color vision lossassociated with early disease/damage/toxicity to (a) alert for earlydisease/damage/toxicity in an effort to (i) provide opportunity fortreatment, and (ii) prevent permanent eye damage, and (b) monitorprogress and treatment of such disease/damage/toxicity.

BACKGROUND OF THE INVENTION

The human eye sees color as a result of three types of receptors, calledcones, listed in the chart below. A range of wavelengths of lightstimulates each of these receptor types to varying degrees.Yellowish-green light, for example, stimulates both L and M conesequally strongly, but only stimulates S-cones weakly; red lightstimulates L cones much more than M cones, and S cones hardly at all;blue-green light stimulates M cones more than L cones, and S cones a bitmore strongly; and blue light stimulates S cones more strongly than redor green light, but L and M cones more weakly. The brain combines theinformation from each type of receptor to give rise to differentperceptions (i.e., colors) of different wavelengths of light.

Cone type Name Range Peak wavelength S B 400-500 nm 420-440 nm M Γ450-630 nm 534-555 nm L P 500-700 nm 564-580 nm

Test procedures such as optical computed tomography (OCT), visual fieldanalyzers, etc., are used primarily to screen and diagnose specific eyedisease. OCTs and visual field analyzers are tests generally used oncethe patient is symptomatic, well after permanent eye damage hasoccurred.

A test, called the Cone Contrast Test (CCT), is used to determinedeficiencies of these cones in an individual's eye. The CCT is explainedin greater detail in the published articles titled “Rapid Quantificationof Color Vision: The Cone Contrast Test” by Rabin et al. published inInvestigative Ophthalmology & Visual Science, February 2011, Vol. 52,No. 2, and “Quantification of Color Vision with Cone ContrastSensitivity” by Jeff Rabin (2004), 21, pp. 483-485, the disclosures ofwhich are hereby incorporated by reference.

The CCT is a functional test, making it a broad, non-disease-specifictest. These features make CCT an affordable screening tool able todetect cone sensitivity degradation associated with a broad spectrum ofdisease/toxicity early enough to, with treatment, potentially preventpermanent eye damage. The CCT may also be used as a predictive test foreye systemic, and neurological disease and retinal toxicity, as well asa monitoring test for disease/toxicity progression and treatment.

Consistent calibration of a color display monitor for administering theCCT is needed. Additionally, a low cost calibration system is needed dueto inconsistent calibration over time. With standard “off-the-shelf”colormeters, interference from other software, including softwareproduced by Microsoft Corporation, override calibration values andrender the test invalid.

SUMMARY OF THE INVENTION

The invention broadly comprises a computerized method for administeringa cone contrast (CCT) color vision test to a patient, comprising thesteps of (a) displaying a first character in a first color at a firstcontrast level on a display driven by the computer; (b) receiving afirst input signal from the patient via an input device connected to thecomputer, where the input signal is indicative of whether the patientrecognizes the first character displayed in the first color at the firstcontrast level; (c) displaying a second character in the first color ata second contrast level on the display driven by the computer; (d)receiving a second input signal from the patient via an input deviceconnected to the computer, where the input signal is indicative ofwhether the patient recognizes the second character displayed in thefirst color at the second contrast level; (e) assigning a score to thefirst and second input signals, the score related to sensitivity of acone in the patient's eye to the first color at the first and secondcontrast levels; and, (f) storing the score in a storage device to trackthe cone sensitivity over time.

The invention also broadly comprises an apparatus for administering acone contrast (CCT) color vision test to a patient, comprising (a) ageneral purpose computer specially programmed for displaying a firstcharacter in a first color at a first contrast level on a display drivenby the computer; (b) means for receiving a first input signal from thepatient via an input device connected to the computer, where the inputsignal is indicative of whether the patient recognizes the firstcharacter displayed in the first color at the first contrast level; (c)means for displaying a second character in the first color at a secondcontrast level on the display driven by the computer; (d) means forreceiving a second input signal from the patient via an input deviceconnected to the computer, where the input signal is indicative ofwhether the patient recognizes the second character displayed in thefirst color at the second contrast level; (e) means for assigning ascore to the first and second input signals, the score related tosensitivity of a cone in the patient's eye to the first color at thefirst and second contrast levels; and, (f) means for storing the scorein a storage device in communication with the computer to track the conesensitivity over time.

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail a preferred embodiment of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to embodiments illustrated.

The invention comprises a method and apparatus for screening andmonitoring progress and treatment of systemic and neurological eyediseases. The method and apparatus include a Cone Contrast Test (CCT)which measures and scores color perception by cone type and assigns ascore by cone type. The method and apparatus further include acomparison of such scores to a base line. Using CCT for the screening ofpotential disease/toxicity is an efficient, fast and low-cost procedure.

The apparatus comprises a computer, including input device and displaydevice, for administering the CCT to individuals and, based on the testresults and other factors, determining the early and late stages of oneof Glaucoma, Retinopathy, Age-Related Macular Degeneration, MultipleSclerosis, potentially Alzheimer's Disease and Parkinson's Disease, aswell as Retinal Toxicity due to high-risk medications, as disclosed inthe Appendices. The method is implemented by the apparatus.

The Cone Contrast Test presents random colored characters (for example,letters, numbers or symbols) to excite the red, green and blue cones indecreasing contrast sensitivity levels to identify the patients' ConeContrast threshold and score for each cone type in each eye. The targetis presented at a size well above a “normal” 20/20 acuity level so thatthe patient's cone contrast score is not affected by a limited acuityability.

Upon each character presentation, the patient selects the correspondingcharacter (for example, a letter, number or symbol) he sees from aresponse table or grid. If he does not see the character presentation,he may select “Pass”.

The patient interface consists of a computer mouse that may be used at adesk or in an exam room at a distance. Future patient interfaces mayinclude a response keypad, notebook, tablet computer, touch screen, orvoice recognition.

The Cone Contrast Test is fully automated, presenting each character fora specific, limited duration. Limiting the presentation time prevents acolor deficient patient from potentially perceiving visual clues to aidhim in his response and potentially affecting his score.

Further, elderly patients may not be familiar with computers, and thusmay not be as responsive even though they are not color deficient. A“blanking period” option may be selected for patients requiring moretime with the response unit. Specifically, after the character ispresented for a fixed duration, the target letter is removed from thescreen. The “blanking period” allows older patients, as well as patientswith physical or cognitive limitations enough time to respond withoutintroducing visual clues that could potentially alter their actualthreshold and score.

Alternatively, an Orientation Screen, presented prior to the test foreach eye, may detect the actual response time for the individual patientand adjust the presentation time for each target letter/number toachieve a Patient-Specific Presentation Time that would accommodate theneed for additional response time due to computer, physical or cognitivelimitations of each individual patient.

The blanking option or patient-specific presentation time is a keycomponent for the Early Eye Disease Detection and Monitoring componentof the Cone Contrast Test, as the majority of patients developing eyedisease are elderly and may need extra time to respond due tounfamiliarity with a computer mouse or physical or cognitivelimitations.

A staircase method is used to present color contrast levels by conetype, allowing the test to be administered more quickly. The contrastpresentations are reduced by two levels at a time if the patientcorrectly identifies the character at that contrast level. The contrastlevel is increased if two or more characters within a contrast level areincorrectly identified.

The colors presented are precisely selected to excite only one cone typeat a time, allowing each cone type to be measured and scoredindependently. Color calibration and contrast calibration are criticalto the validity of the test results.

The equipment is calibrated for both color and contrast. The colorpresentation must be accurate so that each cone type is testedindividually (i.e., only one cone type responds). In turn, the accuracyof the contrast levels is equally important to determine thresholdlevel.

The current system includes software that does not allow other softwareto change color or contrast calibration settings, to achieve a reliablecomputerized color vision test using a low-cost colormeter.

The disclosed system utilizes display calibrating colormeter hardware,such as SPYDER 3™ and related versions, manufactured and sold byDATACOLOR of Lawrenceville, N.J.

Since the CCT begins with establishing a baseline for each cone type foran individual and looks for degradation of the individual's colorperception through repeated testing over time, calibration forrepeatability is critical. Computer equipment and colormeters can bechanged, drift or fail over time, allowing color and contrast values tobecome out of calibration. To ensure that equipment stays withincalibration and test results remain valid, the software forces anautomatic in-field periodic calibration check. The CCT isself-calibrating, requiring the user only to position the photometer onthe monitor and start the calibration. The calibration verification isdone automatically and checks calibration values to original calibrationvalues done at initial manufacturing. If the calibration is outside oftolerance, the system forces a complete calibration. If the calibrationis still outside of tolerance, the system will alert the user anddisable the use of the Cone Contrast Test until calibration can becompleted within tolerance.

The duration between each calibration is established during set-up andmay be adjusted based on clinic testing policy and procedure. Thecalibration time frame is pre-set for every seven days, but may be setaccording to individual testing policy and preference. Preferably,calibration automatically occurs at a predetermined interval of time.The automation alleviates the fear by some that the calibration may beskipped and test results may be rendered invalid.

Automated calibration verification enables a user of the invention tocheck for failing/failed hardware, including colormeter, monitor, orcomputer changes to ensure valid test scores. The calibrationverification of the present system is preferably set at a seven (7) dayinterval, requiring calibration be checked against the originalcalibration settings. Any significant change from original calibrationsettings requires a full calibration. If a full calibration is stilloutside of tolerances, the Cone Contrast Test is disabled until acalibration can be completed within tolerance. Replacing equipment, suchas a photometer, monitor or CPU, may be required to achieve a validcalibration.

Since the equipment may be used for both screening and monitoring ofdisease/toxicity, the equipment has both a screening mode and acomprehensive testing mode to allow for Medicare or other insurancebilling, with the comprehensive mode providing more thorough examinationand reporting. A doctor specifies the mode based on the use of theinstrument for the specific exam before conducting the test.

Variations in the testing method may include, but are not limited to (1)altering distance between screen and individual (e.g., 3, 4 or 6meters), (2) a user interface such as voice recognition commands,wireless keyboard or other wired or wireless input devices, (3) blankingperiod or patient-specific response time, and (4) screening and testingmodes.

Each test is scored by cone type and any cone deficiency is determinedby comparing the patient's scores over time. Accuracy of CCT is veryhigh in detecting Red, Green and Blue cone deficiencies. Deficiencieswhich present over time are predictive of early eye, systemic andneurological disease as well as retinal toxicity, whereas suchdeficiencies may otherwise be overlooked as anomalies.

Storing of cone contrast sensitivity scores and reporting data in a waythat shows cone contrast sensitivity changes over time allows forpotential disease/toxicity alerts. Reports show a change in conecontrast sensitivity by patient, per eye, by cone type and display analert when the cone contrast sensitivity change is statisticallysignificant. The reports can be viewed or printed to alert doctors andpatients of potential disease or toxicity that should be furtherinvestigated.

Currently, significant change is thought to be the normal distributionof color normal patients score, >15 points. Further research may showthat changes less than 15 points may also be significant to a specificpatient baseline.

This type of tracking and reporting mechanism has never before beenavailable, limiting prior art systems and methods to hereditary colordeficiency scoring use or research where time permits for manualcomparison. The disclosed system and method is the first CCT usable asan early eye, systemic and neurological disease and retinal toxicitydetection system in a clinic setting, where time with the patient islimited. Comparison data and alerts are critical to interpret testresults in the time frame required in a clinical setting.

Patient reports are stored on the computer hard drive and may beuploaded to electronic medical records.

As previously discussed, patient response time is captured and recordedfor each cone type for every Cone Contrast Test. Mean response time bycone type, and by eye, is calculated and reported. Response times havebeen shown to correlate closely with cone deficiency, with color normalpatients responding consistently within two seconds and color deficientpatients responding much slower. Cone Contrast Sensitivity Response Timemay serve as a new sensitive metric of color deficiency and earlyindicator of eye, systemic or neurological disease.

The matter set forth in the foregoing description and accompanyingdrawings is offered by way of illustration only and not as a limitation.While particular embodiments have been shown and described, it will beapparent to those skilled in the art that changes and modifications maybe made without departing from the broader aspects of applicants'contribution.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are disclosed, by way of example only, withreference to the accompanying drawings in which corresponding referencesymbols indicate corresponding parts, in which:

FIG. 1 is a screen shot of the invention;

FIG. 2 is a screen shot of the invention;

FIG. 2 a is an enlarged view of the enclosed region 2 a shown in FIG. 2;

FIG. 2 b is an enlarged view of the enclosed region 2 b shown in FIG. 2;

FIG. 3 is a screen shot of the invention;

FIG. 3 a is an enlarged view of the enclosed region 3 a shown in FIG. 3;

FIG. 3 b is an enlarged view of the enclosed region 3 b shown in FIG. 3;

FIG. 4 is a screen shot of the invention;

FIG. 5 is a screen shot of the invention;

FIG. 6 is a screen shot of the invention;

FIG. 7 is a screen shot of the invention;

FIG. 8 is a screen shot of the invention;

FIG. 9 is a screen shot of the invention;

FIG. 10 is a screen shot of the invention;

FIG. 11 is a screen shot of the invention;

FIG. 12 is a screen shot of the invention;

FIG. 13 is a screen shot of the invention;

FIG. 14 is a screen shot of the invention;

FIG. 15 is a report of the invention;

FIG. 15 a is an enlarged view of the enclosed region 15 a shown in FIG.15;

FIG. 16 is a report of the invention;

FIG. 16 a is an enlarged view of the enclosed region 16 a shown in FIG.16;

FIG. 17 is a report of the invention;

FIG. 17 a is an enlarged view of the enclosed region 17 a shown in FIG.17;

FIG. 18 is a report of the invention;

FIG. 18 a is an enlarged view of the enclosed region 18 a shown in FIG.18;

FIG. 19 is a screen shot of the invention;

FIG. 20 is a screen shot of the invention;

FIG. 21 is a report of the invention;

FIG. 22 is a report of the invention;

FIG. 23 is a diagram of the invention;

FIG. 23 a is an enlarged view of the enclosed region 23 a shown in FIG.23;

FIG. 23 b is an enlarged view of the enclosed region 23 b shown in FIG.23;

FIG. 24 is a diagram of the invention;

FIG. 24 a is an enlarged view of the enclosed region 24 a shown in FIG.24; and,

FIG. 24 b is an enlarged view of the enclosed region 24 b shown in FIG.24.

DETAILED DESCRIPTION

At the outset, it should be appreciated that like drawing numbers ondifferent drawing views identify identical, or functionally similar,structural elements of the embodiments set forth herein. Furthermore, itis understood that these embodiments are not limited to the particularmethodology, materials and modifications described and as such may, ofcourse, vary. It is also understood that the terminology used herein isfor the purpose of describing particular aspects only, and is notintended to limit the scope of the disclosed embodiments, which arelimited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which these embodiments belong.

Moreover, although any methods, devices or materials similar orequivalent to those described herein can be used in the practice ortesting of these embodiments, some embodiments of methods, devices, andmaterials are now described.

As discussed above, a cone contrast test presents characters with colorsspecific to each cone type in decreasing contrast steps down to or nearthe patient's cone contrast threshold. It tests all three colorvalues—red, green and blue—in both right and left eyes. Characters oroptotypes are presented at 20/300 (red, green) and 20/400 (blue) toavoid acuity function interference. The CCT presents 5 contrast levelsin increments of two contrast levels or jumps until the patient respondsincorrectly. At that time, the contrast level presentations begin at thenext higher contrast level and proceeds in a sequential fashion throughthe duration of the test. The patient's cone score is determined basedon the number of correct responses at each level.

Adverting now to the Figures, the following Figures show screenshots oftesting software 100. FIG. 1 shows sign in screen 101 driven by acomputer. Sign in screen 101 comprises user name field 102, passwordfield 103, and sign in button 104. Upon commencing testing software 100,sign in screen 101 appears. In order to access testing software 100, apatient taking a CCT or an administrator directing the CCT, must input auser name and a password into user name field 102 and password field103, respectively. A user can exit testing software 100 by selectingexit button 105 located at the top right of sign in screen 101.

Once sign in button 104 is selected, presentation option screen 106 oftesting software 100 appears as shown in FIG. 2. Presentation optionscreen 106 comprises CCT near button 108, CCT distance button 109,contrast acuity near button 110, contrast acuity distance button 111,contrast sensitivity distance button 112, and reports button 113. TheCCT may be conducted while a patient is seated at a desk with thecomputer displaying the CCT mounted thereon. In this case, a patient canuse a computer mouse or some other means to select buttons in testingsoftware 100 to be described in more detail below. Alternatively, theCCT may be conducted while a patient is seated or standing a distancefrom the computer displaying the CCT. In this case, an administratordirecting or overseeing the CCT can operate a mouse connected to thecomputer displaying the CCT or some other interface may be involved toinput a patient's responses. For example, voice recognition softwarecould be used to transmit a patient's selections in or responses to theCCT, or a wireless mouse could be used. Regardless of the method used,acuity and cone contrast tests can be administered with a patientarranged proximate the display screen and at a distance away from thedisplay screen. For near testing, a patient should be 18-24 inches fromthe display. For tests administered at a distance, a patient should beat least 9 feet from the display. If CCT near button 108 or contrastacuity near button 110 is selected, testing software 100 is directed touse characters at a default size based on the calibration of testingsoftware 100. If CCT distance button 109 is selected, testing software100 is directed to display higher quality characters, down to 20/10,during the CCT depending on the patient's distance from the computerdisplay. Selecting CCT distance button 109 will cause testing software100 to produce a distance field and the patient's distance from thecomputer display will need to be inputted into the distance field andtransmitted to testing software 100 so the proper quality characters areused. For best results, the patient should be parallel to the display.Selecting contrast acuity distance button 111 or contrast sensitivitydistance button 112 will similarly direct testing software 100 to usehigher quality characters, down to 20/10, during the acuity orsensitivity tests depending on the patient's distance from the computerdisplay. Reports button 113 will be discussed in more detail below.FIGS. 2 a and 2 b represent enlarged enclosed areas 2 a and 2 b,respectively, shown in FIG. 2.

The CCT should be conducted in dim room lighting. No light should bedirected at the CCT display. However, some lighting is acceptable andwill not interfere with the test.

Selection of the type of test desired (CCT near button 108, CCT distancebutton 109, contrast acuity near button 110, contrast acuity distancebutton 111, or contrast sensitivity distance button 112) will directtesting software 100 to produce subject data screen 116. Subject datascreen 116 comprises patient ID field 114 and patient name field 115shown in FIG. 3. Patient ID field 114 of testing software 100 isarranged to receive a 1-10 digit number identifying a patient. Thenumber can but input using a keyboard, for example. Left and rightarrows on a keyboard allow a user to move between digit entry fields. Apatient's name, for example, John Doe is inputted into patient namefield 115 using a keyboard, for example. It should be appreciated thatother means such as, voice recognition software could be used topopulate patient ID field 114 and patient name field 115. To start thetest, a patient or an administrator presses the “Enter” button on akeyboard. The test can be started without inputting data into patient IDfield 114 and patient name field 115. A user can exit testing software100 by selecting exit button 105 located at the top right of subjectdata screen 116. FIGS. 3 a and 3 b represent enlarged enclosed areas 3 aand 3 b, respectively, shown in FIG. 3.

The CCT test can be implemented using any characters preferably, lettersor numbers. For Dyslexic patients, conducting the test using numbers mayyield more favorable results. To present the test with letters, pressthe R-CCT button on the remote control or the STAIR button on thescreen. Using the keyboard, press Shift F1. To present the test withnumbers, first select the NUM button on the remote control. Then pressR-CCT on the remote control or the STAIR button on the screen.

FIG. 4 shows orientation testing screen 200. Orientation testing screen200 comprises orientation instruction pane 201, confirmation button 203,testing field 211, testing symbol 212, response table 213, and passbutton 214. Response table 213 comprises plurality of response symbols215. In some embodiments of the invention, orientation testing screen200 is displayed immediately upon commencement of the visual acuity testprocess. By displaying orientation testing screen 200 prior to otherportions of the visual acuity test, the method of taking the visualacuity test can be relayed and practiced by the patient taking thevisual acuity test. Orientation instruction pane 201 contains writteninstructions on the specific steps the patient taking the visual acuitytest should take during the testing process. Orientation instructionpane 201 also contains instructions for advancing to the other portionsof the visual acuity test.

In the embodiment of the invention shown in FIG. 4, the writteninstructions in orientation instruction pane 201 instruct the patienttaking the visual acuity test to identify testing symbol 212 in testingfield 211 and select the equivalent symbol from the plurality ofresponse symbols 215 in response table 213. In some embodiments of theinvention, the specific symbols included in response table 213 will beselected randomly, but in all embodiments of the invention, a symbolequivalent to testing symbol 212 must be one of response symbols 215 inresponse table 213.

This initial selection of one of the symbols of the plurality ofresponse symbols 215 in response table 213 highlights the selectedsymbol for review by the patient. In some embodiments of the invention,selecting one of the plurality of response symbols 215 will causetesting software 100 to produce a sound corresponding to the symbolselected, such as saying the name of the letter if the plurality ofresponse symbols 215 are letters. Selecting the same symbol again willact as a confirmation and indicate to testing software 100 that thepatient believes the symbol selected from the plurality of responsesymbols 215 in response table 213 to be the same as the testing symbol212.

If the patient taking the visual acuity test cannot identify testingsymbol 212, the patient may select pass button 214. This will indicateto testing software 100 that the patient is unable to identify testingsymbol 212. In some embodiments of the invention, selecting the passbutton will be recorded as an incorrect identification for patientvisual acuity assessment purposes.

Upon confirmation of a symbol from the plurality of response symbols 215in response table 213 or selection of pass button 214, testing software100 will record the response and orientation testing screen 200 willrefresh. Upon refreshing, orientation testing screen will display a newtesting symbol 212 and response table 213 will comprise a differentplurality of response symbols 215. The patient taking the visual acuitytest will then select one of the plurality of response symbols 215 inresponse table 213 or pass button 214, continuing the orientationprocess. When the patient is confident that he or she understands themethod of taking the visual acuity test, the orientation process can beended by selecting the confirmation button 203.

FIG. 5 shows test commencement screen 230. Test commencement screen 230comprises commencement message 231, confirmation button 203, responsetable 213, and pass button 214. Response table 213 comprises pluralityof response symbols 215. Test commencement screen 230 is displayedimmediately prior to the commencement of the testing portions of thevisual acuity test to announce that the test process is ready to begin.The patient taking the visual acuity test will select confirmationbutton 203 when they are ready to begin the testing process. Althoughresponse table 213 and pass button 214 are components of testcommencement screen 230, they are not active, i.e., they cannot beselected.

FIG. 6 shows eye selection screen 232. Eye selection screen 232comprises eye selection message 233, confirmation button 203, responsetable 213, and pass button 214. Response table 213 comprises pluralityof response symbols 215. Eye selection screen 232 is displayedimmediately prior to each of the two eye-specific portions of the visualacuity test. As visual acuity can be different in the left and righteyes of the patient taking the visual acuity test, it is beneficial totest the left and right eyes individually. By testing the left and righteyes individually, a more thorough understanding of the patient's visualacuity can be obtained.

Eye selection message 233 indicates which eye will be tested in thefollowing test portion. For example, if the right eye is to be tested inthe following test portion, eye selection message 233 would instruct thepatient to cover their left eye and perform the test with their righteye only. The patient taking the visual acuity test will selectconfirmation button 203 when they are ready to begin the testing processfor the eye indicated in eye selection message 233. Although responsetable 213 and pass button 214 are components of eye selection screen232, they are not active, i.e., they cannot be selected.

FIG. 7 shows color phase screen 234. Color phase screen 234 comprisescolor phase message 235, response table 213, and pass button 214.Response table 213 comprises plurality of response symbols 215. Colorphase screen 234 is displayed immediately prior to each of the threecolor-specific phases of the visual acuity test.

The ability of humans to perceive different colors of light is madepossible by specialized cells in the retina called cone cells. Each ofthe three different types of cone cells detects a different portion ofthe visual spectrum, and each type is most sensitive to a certain colorof light. The three different types of cone cells are most sensitive tocolors that correspond approximately to the colors of red, green, andblue. Colors other than red, green, and blue are perceived via thecombination in the human brain of signals from multiple types of conecells and their relative intensities. For example, the color yellow isperceived when the red and green cone cells are stimulated approximatelyequally. The phenomenon of perceiving the full spectrum of visible lightbased on the combination of signals from three types of cells, each ofwhich detects a different color, is called trichromasy.

As human vision is trichromatic, deficiencies in one or more of thetypes of cone cells can impair the ability of an individual to perceivecertain colors. However, because each type of cone cell is mostsensitive to a certain color of light, it is possible to individuallyassess the sensitivity of cone cells of a certain type by testing theability to distinguish image components made of the color that thecorresponding type of cone cell is most sensitive to. For this reason,the visual acuity test has three phases for each eye, a red phase, agreen phase, and a blue phase. For example, in the red phase, thesensitivity of the red-type cone cells is assessed. In this way, thesensitivities of the red-type, green-type, and blue-type cone cells ineach eye can be assessed.

Color phase message 235 announces to the patient taking the visualacuity test which color phase is about to begin. As the patient does notneed to prepare for the specific color phases, the patient does not haveto select any particular interface component to continue to the portion.The test process will continue automatically after a predeterminedamount of time. Although response table 213 and pass button 214 arecomponents of color phase screen 234, they are not active, i.e., theycannot be selected.

FIG. 8 shows testing screen 210. Testing screen 210 comprises testingfield 211, testing symbol 212, response table 213, and pass button 214.Response table 213 comprises plurality of response symbols 215. Havingfamiliarized themselves with the testing method during the orientationportion of the visual acuity test, the patient taking the test will beable to perform the test without further instruction. Testing symbol212, is either red, green, or blue, depending on which color phase thetesting process is currently in. For example, in the red color phase ofthe testing process, testing symbol 212 will be red.

The sensitivities of the different types of cone cells is assessed byshowing the patient taking the visual acuity test a testing symbol 212of the color corresponding the present color phase on testing field 211.Initially, there is a large contrast differential between testing symbol212 and testing field 211. Due to this high contrast differential, it iseasier for the patient to distinguish the shape of testing symbol 212and select the equivalent symbol from the plurality of response symbols215 in response table 213. By iteratively reducing the contrastdifferential between testing symbol 212 and testing field 211 and askingthe patient to select the equivalent symbol from the plurality ofresponse symbols 215 in response table 213, until the patient is unableto correctly identify testing symbol 212, the ability of the specificcone cell types of the patient's specific eye can be assessed.

In some embodiments of the invention, the specific symbols included inresponse table 213 will be selected randomly, but in all embodiments ofthe invention, a symbol equivalent to testing symbol 212 must be one ofresponse symbols 215 in response table 213.

This initial selection of one of the symbols of the plurality ofresponse symbols 215 in response table 213 highlights the selectedsymbol for review by the patient. In some embodiments of the invention,selecting one of the plurality of response symbols 215 will causetesting software 100 to produce a sound corresponding to the symbolselected, such as saying the name of the letter if the plurality ofresponse symbols 215 are letters. Selecting the same symbol again willact as a confirmation and indicate to testing software 100 that thepatient believes the symbol selected from the plurality of responsesymbols 215 in response table 213 to be the same as the testing symbol212.

If the patient taking the visual acuity test cannot identify testingsymbol 212, the patient may select pass button 214. This will indicateto testing software 100 that the patient is unable to identify testingsymbol 212. In some embodiments of the invention, selecting the passbutton will be recorded as an incorrect identification for patientvisual acuity assessment purposes. Additionally, in some embodiments ofthe invention, if the patient does not select any of the plurality ofresponse symbols 215 in response table 213 in a predetermined amount oftime, such inaction will be recorded as an incorrect identification forpatient visual acuity assessment purposes. The predetermined amount oftime before an incorrect identification is registered may be varieddepending on the purpose of the visual acuity test. For example, if thepurpose of the test is to measure the ability of piloting students todistinguish colors, the ability to make timely determinations may bemore important than if the purpose of the test is to test generally forcolor-blindness. In such a case, the predetermined amount of time beforean incorrect identification is registered may be reduced.

If the patient correctly identifies testing symbol 212 by selecting theequivalent symbol from the plurality of response symbols 215 in responsetable 213, testing software 100 will record a correct identification andcontinue the test process. In one embodiment of the invention, twocorrect identifications in succession by the patient at a specificcontrast differential level will cause testing software 100 to display atesting screen 210 with a testing symbol 212 two contrast differentiallevels lower than the immediately preceding testing symbol 212.

If the patient selects an incorrect response symbol from the pluralityof response symbols 215 in response table 213, then testing software 100will record an incorrect identification. If the patient selects passbutton 214, then testing software 100 will record that the patient choseto pass. In an embodiment of the invention, if the patient selects anincorrect response symbol from the plurality of response symbols 215 inresponse table 213, the testing software will display a testing screen210 with a testing symbol 212 one contrast differential level higherthan the immediately preceding testing symbol 212.

In yet another embodiment of the invention, if the patient correctlyidentifies two testing symbols 212 of a given contrast differentiallevel, even if such correct identification is separated by an incorrectidentification, or a selection of pass button 214, or the registering ofan incorrect identification by the lapsing of the predetermined amountof time, then the testing software will display a testing screen 210with a testing symbol 212 one contrast differential level lower than theimmediately preceding testing symbol 212.

Generally, testing software 100 will start each phase of the testprocess by displaying a testing screen 210 with a testing symbol 212 ofa maximum contrast differential with testing field 211. Upon registeringa predetermined number of correct identifications of testing symbols212, testing software 100 will begin displaying a series of testingscreens 210 with testing symbols 212 of a lower contrast differentialwith testing field 211. Upon registering a predetermined number ofincorrect identifications, or selections of pass button 214, or lapsesof the predetermined amount of time, testing software 100 will begindisplaying a series of testing screens 210 with testing symbols 212 of ahigher contrast differential with testing field 211. The testing processin a specific color phase will end after a predetermined number ofcorrect identifications are registered at a specific contrastdifferential level. Registering a large number of correctidentifications at a specific contrast differential level indicates thatthe patient cannot reliably distinguish and identify a testing symbol212 of lower contrast differential levels. The testing process in aspecific color phase may also end after pass button 214 has beenselected a predetermined number of times. Repeatedly selecting passbutton 214 indicates that the patient can no longer reliably distinguishand identify the series of testing symbols 212 that are being displayed.

FIG. 9 shows refreshed testing screen 210 comprising testing field 211,testing symbol 212 of reduced contrast differential with testing field211, response table 213, and pass button 214. Response table 213comprises plurality of response symbols 215. The patient taking thevisual acuity test will attempt to correctly distinguish and identifytesting symbol 212 and select the corresponding symbol from theplurality of response symbols 215. If the patient is unable todistinguish and identify testing symbol 212, they may select pass button214 to cause testing software 100 to display new testing screen 210.

FIG. 10 shows refreshed testing screen 210 comprising testing field 211,testing symbol 212 of further reduced contrast differential with testingfield 211, response table 213, and pass button 214. Response table 213comprises plurality of response symbols 215. The patient taking thevisual acuity test will attempt to correctly distinguish and identifytesting symbol 212 and select the corresponding symbol from theplurality of response symbols 215. If the patient is unable todistinguish and identify testing symbol 212, they may select pass button214 to cause testing software 100 to display new testing screen 210.

FIG. 11 shows refreshed testing screen 210 comprising testing field 211,testing symbol 212 of even further reduced contrast differential withtesting field 211, response table 213, and pass button 214. Responsetable 213 comprises plurality of response symbols 215. The patienttaking the visual acuity test will attempt to correctly distinguish andidentify testing symbol 212 and select the corresponding symbol from theplurality of response symbols 215. If the patient is unable todistinguish and identify testing symbol 212, they may select pass button214 to cause testing software 100 to display new testing screen 210.

FIG. 12 shows refreshed testing screen 210 comprising testing field 211,testing symbol 212 of minimal contrast differential with testing field211, response table 213, and pass button 214. Response table 213comprises plurality of response symbols 215. The patient taking thevisual acuity test will attempt to correctly distinguish and identifytesting symbol 212 and select the corresponding symbol from theplurality of response symbols 215. If the patient is unable todistinguish and identify testing symbol 212, they may select pass button214 to cause testing software 100 to display new testing screen 210.

Upon completion of a specific color phase in the testing process,testing software 100 will continue to the next color phase for thecurrently tested eye. If all color phases have been completed for thecurrently tested eye, testing software 100 will display eye selectionscreen 232 and continue the testing process with the next eye to betested. If all color phases for both eyes have been completed, the testprocess is complete.

FIG. 13 shows test conclusion screen 236. Test conclusion screen 236comprises conclusion message 237, response table 213, and pass button214. Conclusion message 237 informs the patient that the test process iscomplete. Although response table 213 and pass button 214 are componentsof test commencement screen 230, they are not active, i.e., they cannotbe selected.

Viewing and Interpreting Results

Reports may be generated by patient, type of report, and dates. Togenerate a report for a particular patient, testing software 100 isarranged to select data connected to a patient ID. You may display alist of all tests for a patient as shown in FIG. 19. Or, to printComparison Reports, select the type of report to be displayed, and thenselect the date range for the report. Use the mouse or TAB key to movebetween the types of reports. Double click or hit ENTER on the specificreport date to view specific exam results. Selecting Dates forComparison Reports to view comparison results select the date range tobe displayed. To display reports within a narrower time frame, forexample, since the beginning of treatment, you may select a subset ofthe available tests. Hold down the SHIFT key to select a date range orhold down the CTRL key to select specific tests. Use the PgUp and PgDnbuttons to select larger date ranges. When the desired test dates areselected, click or TAB to the Submit for Report Generation button toview the report.

Reports button 113 shown in FIG. 2 can be accessed to review andgenerate test results. Similarly, FIG. 14 shows report generator screen500. Report generator screen 500 comprises select all test dates button501 and submit for report generation button 502. If select all testdates button 501 is selected, testing software 100 is directed toinclude all test data in generating reports for interpretation. Ifselect all test dates button 501 is not selected, particular test datescan be selected from report generator screen 500. Once particular testdates are selected from report generator screen 500, for example,selected test date 503, selection of submit for report generation button502 directs testing software 100 to generate reports.

Reports are shown in FIGS. 15-18, 21-22. Significantly, CCT scores areshown in red, green and blue. Red CCT scores are shown with a singledashed line connecting circles. Green CCT scores are shown as a barconnecting squares. Blue CCT scores are shown as a double dashed lineconnecting triangles. The circles, squares and triangles refer to CCTscores. The lines connecting the CCT scores are generated to show trendsand whether a patient's aptitude for color vision is deteriorating. Somereports include bar graphs (FIG. 16) and line graphs (FIG. 17). Thecolors red, yellow and green are also used to indicate color deficiency,possible deficiency, and normal vision, respectively. FIGS. 15 a, 16 a,17 a, and 18 a show the enclosed areas 15 a, 16 a, 17 a, and 18 a,respectively, shown in FIGS. 15, 16, 17, and 18, respectively, enlargedfor clarity. FIGS. 23 a, 23 b, 24 a, and 24 b show the enclosed areas 23a, 23 b, 24 a, and 24 b, respectively, shown in FIGS. 23 and 24,respectively, enlarged for clarity.

Acquired and hereditary color deficiency can be interpreted based on aless than normal cone score in a single visit or as a drop in a specificcone score of 10 points or more from a patient's base-line. Normal colorvision is indicated by a CCT score between 90-100. Possible color visiondeficiency is indicated by a CCT score between 75-89. Color deficiency,hereditary or acquired, is indicated by a CCT score between 0-74.Acquired and hereditary color deficiency overlap. However, there areseveral characteristics that can help identify acquired vs. hereditarycolor deficiency. Hereditary color deficiency is indicated by selectivedecreases on red or green tests. Moreover, cone sensitivity scores aresubstantially symmetrical in the left and right eyes. In contrast,acquired color deficiency is not as selective to cone types and may showdecreases on red, green and blue tests. Acquired color deficiency alsousually features asymmetrical cone sensitivity scores in the left andright eyes.

Thus, it is seen that the objects of the present invention areefficiently obtained, although modifications and changes to theinvention should be readily apparent to those having ordinary skill inthe art, which modifications are intended to be within the spirit andscope of the invention as claimed. It also is understood that theforegoing description is illustrative of the present invention andshould not be considered as limiting. Therefore, other embodiments ofthe present invention are possible without departing from the spirit andscope of the present invention.

What is claimed is:
 1. A computerized method for administering a conecontrast (CCT) color vision test to a patient, comprising the steps of:(a) displaying a first character in a first color at a first contrastlevel on a display driven by said computer; (b) receiving a first inputsignal from said patient via an input device connected to said computer,where said input signal is indicative of whether said patient recognizessaid first character displayed in said first color at said firstcontrast level; (c) displaying a second character in said first color ata second contrast level on said display driven by said computer; (d)receiving a second input signal from said patient via an input deviceconnected to said computer, where said input signal is indicative ofwhether said patient recognizes said second character displayed in saidfirst color at said second contrast level; (e) assigning a score to saidfirst and second input signals, said score related to sensitivity of acone in said patient's eye to said first color at said first and secondcontrast levels; and, (f) storing said score in a storage device totrack said cone sensitivity over time.
 2. The computerized method fordetecting color vision loss in a patient recited in claim 1, whereinsaid second contrast level is lower than said first contrast level. 3.The computerized method for detecting color vision loss in a patientrecited in claim 1, further comprising the step of displaying said scoreon a computer display.
 4. The computerized method for detecting colorvision loss in a patient recited in claim 1, repeating the steps of (a)through (e) of claim 1 with a second color.
 5. The computerized methodfor detecting color vision loss in a patient recited in claim 1,repeating the steps of (a) through (e) of claim 1 with a third color. 6.The computerized method for administering a color vision test in apatient recited in claim 1, further comprising the steps of periodicallyverifying a calibration of said first color and said first contrastlevel of said first character to be displayed on said display, wheresaid verifying is accomplished by software.
 7. The computerized methodfor detecting color vision loss in a patient recited in claim 6, whereinthe step of verifying a calibration is automatic if said calibrationfails.
 8. The computerized method for detecting color vision loss in apatient recited in claim 1, wherein said first color is red.
 9. Thecomputerized method for detecting color vision loss in a patient recitedin claim 1, wherein said first color is green.
 10. The computerizedmethod for detecting color vision loss in a patient recited in claim 1,wherein said first color is blue.
 11. The computerized method fordetecting color vision loss in a patient recited in claim 1, whereinsaid cone is an S cone.
 12. The computerized method for detecting colorvision loss in a patient recited in claim 1, wherein said cone is an Mcone.
 13. The computerized method for detecting color vision loss in apatient recited in claim 1, wherein said cone is an L cone.
 14. Thecomputerized method for detecting color vision loss in a patient recitedin claim 1, further comprising the steps of imposing a limitedpresentation time for steps (a) and (c).
 15. The computerized method fordetecting color vision loss in a patient recited in claim 1, furthercomprising the step of alerting said patient of said CCT if said scoreindicates significant degradation.
 16. The computerized method fordetecting color vision loss in a patient recited in claim 1, furthercomprising the step of generating reports of said score.
 17. Thecomputerized method for detecting color vision loss in a patient recitedin claim 4, wherein said second color is red.
 18. The computerizedmethod for detecting color vision loss in a patient recited in claim 4,wherein said second color is green.
 19. The computerized method fordetecting color vision loss in a patient recited in claim 4, whereinsaid second color is blue.
 20. The computerized method for detectingcolor vision loss in a patient recited in claim 5, wherein said thirdcolor is red.
 21. The computerized method for detecting color visionloss in a patient recited in claim 5, wherein said third color is green.22. The computerized method for detecting color vision loss in a patientrecited in claim 5, wherein said third color is blue.
 23. Thecomputerized method for detecting color vision loss in a patient recitedin claim 1, wherein said first character is a letter.
 24. Thecomputerized method for detecting color vision loss in a patient recitedin claim 1, wherein said first character is a number.
 25. Thecomputerized method for detecting color vision loss in a patient recitedin claim 1, wherein said first character is a symbol.
 26. Thecomputerized method for detecting color vision loss in a patient recitedin claim 1, further comprising the step of differentiating said scorebetween hereditary and acquired deficiency.
 27. The computerized methodfor detecting color vision loss in a patient recited in claim 1, furthercomprising the step of differentiating said score between normal,possible deficiency, mild deficiency, moderate deficiency, and severedeficiency.
 28. An apparatus for administering a cone contrast (CCT)color vision test to a patient, comprising: (a) a general purposecomputer specially programmed for displaying a first character in afirst color at a first contrast level on a display driven by saidcomputer; (b) means for receiving a first input signal from said patientvia an input device connected to said computer, where said input signalis indicative of whether said patient recognizes said first characterdisplayed in said first color at said first contrast level; (c) meansfor displaying a second character in said first color at a secondcontrast level on said display driven by said computer; (d) means forreceiving a second input signal from said patient via an input deviceconnected to said computer, where said input signal is indicative ofwhether said patient recognizes said second character displayed in saidfirst color at said second contrast level; (e) means for assigning ascore to said first and second input signals, said score related tosensitivity of a cone in said patient's eye to said first color at saidfirst and second contrast levels; and, (f) means for storing said scorein a storage device in communication with said computer to track saidcone sensitivity over time.
 29. The apparatus recited in claim 28,wherein said second contrast level is lower than said first contrastlevel.
 30. The apparatus recited in claim 28, further comprising meansfor displaying said score on a computer display.
 31. The apparatusrecited in claim 28, further comprising means for periodically verifyinga calibration of said first color and said first contrast level of saidfirst character to be displayed on said display, where said verifying isaccomplished by software.
 32. The apparatus recited in claim 28, whereinsaid means of verifying a calibration is operatively arranged tofunction automatically if said calibration fails.
 33. The apparatusrecited in recited in claim 28, wherein said first color is red.
 34. Theapparatus recited in claim 28, wherein said first color is green. 35.The apparatus recited in claim 28, wherein said first color is blue. 36.The apparatus recited in claim 28, wherein said cone is an S cone. 37.The apparatus recited in claim 28, wherein said cone is an M cone. 38.The apparatus recited in claim 28, wherein said cone is an L cone. 39.The apparatus recited in claim 28, further comprising means for imposinga limited presentation time for displaying said first and secondcharacters.
 40. The apparatus recited in claim 28, further comprisingmeans for alerting said patient of said CCT if said score indicatessignificant degradation.
 41. The apparatus recited in claim 28, furthercomprising means for generating reports of said score.
 42. The apparatusrecited in claim 28, wherein said first character is a letter.
 43. Theapparatus recited in claim 28, wherein said first character is a number.44. The apparatus recited in claim 28, wherein said first character is asymbol.
 45. The apparatus recited in claim 28, further comprising meansfor differentiating said score between hereditary and acquireddeficiency.
 46. The apparatus recited in claim 28, further comprisingmeans for differentiating said score between normal, possibledeficiency, mild deficiency, moderate deficiency, and severe deficiency.